This canon, I confess, is contained in all the editions
of the Commentaries of Balsamon and Zonaras. It is cited also by
Photius in Nomocanon, Tit. xii. ch. xiv., besides it is extant
in a contracted form in the Epitome of Alexius Aristenus. But it
is wanting in all the Latin versions of the Canons, in the ancient
translations of Dionys. Exig., Isidore Mercator, etc.; also in the
Epitome of Sym. Logothet., and the Arabic paraphrase of Josephus
Ægyp., and what is particularly to be observed, in the collection
and nomocanon of John of Antioch; and 185this not through want of attention on his part,
as is clear from this namely, that in the order of the Canons as given
by him he attributes six Canons only to this second General Council,
saying “…of the Fathers who assembled at Constantinople, by
whom six Canons were set forth,” so that it is clear the present
was not reckoned among the canons of this council in those days.
Nay, the whole composition of this canon clearly indicates that it is
to be ascribed, neither to this present council, nor to any other
(unless perhaps to that of Trullo, of which we shall speak
afterwards). For nothing is appointed in it, nothing confirmed,
but a certain ancient custom of receiving converted heretics, is here
merely recited.

(Hefele, History of the Councils, Vol. II., p.
368.)

As we possess a letter from the Church at Constantinople
in the middle of the fifth century to Bishop Martyrius of Antioch, in
which the same subject is referred to in a precisely similar way,
Beveridge is probably right in conjecturing that the canon was only an
extract from this letter to Martyrius; therefore in no way a decree of
the second General Council, nor even of the Synod of 382, but at least
eighty years later than the latter. This canon, with an addition,
was afterwards adopted by the Quinisext Synod as its ninety-fifth,
without, however, giving its origin.